Warhol had a type of intelligence that does not register well on IQ tests. I am not all that impressed with his works, either. But he had a knack for making people realize that even commercial art like soup cans and such has a degree of artistic organization to it, and can be looked upon as a form of art.
Art is art, but the official art world will look at a painting and say that it is average for the period. Then you tell them that it was done by DaVinci or Picasso and suddenly, they see it as a masterpiece. That is just silly.
There is this story that someone brought Picasso a painting he had just purchased,and ask him if it was a fake. Picasso looked at it for a while and said, "yes." The owner said, "well, here I have a signed certificate! Is this your signature?" Picasso said, "yes, the signature is mine. But I often paint fakes." Or words to that effect.
Meaning that he painted it for money, not because he was in an artistic mood when he did it.
I sort of question any comparison of IQ's of people unless they took the same exact test: the pre-1900's examples are estimates, and I imagine that some of the others are as well.